Safety guards for brakes



Dec. 11, 1962 REZNICK 3,067,798

SAFETY GUARDS FOR BRAKES Filed July 27, 1960 INVENTOR, LOUIS REZNIC'K,

ATTORNEY States llnite The present invention relates to safety guards for power-driven machinery and more particularly to a type adaptable for use on power brakes.

A power brake is a machine for bending metal sheets and essentially includes a ram carrying a male die part, movable therewith towards and then away from the female die part mounted on a fixed bed. The female die part is an upright channel. In operating the machine to make a bend, the sheet portion in front of the die, is swung upward with extreme rapidity. In the trade, this occurrence is called whip. The safety guard must of course be in front of the die and offer clearance for feeding a sheet between the die parts and yet guard against the entrance of a finger.

An object of this invention is to provide a novel safety guard for a power brake, which will be automatically shifted in proper time to allow the speedy upward movement of the whipped forward portion of the work so that such movement is unmolested. The guard will of course work equally as well, if the ram movement is slow.

A further object thereof is to provide a novel safety guard of the character mentioned, in which the movement of the whipped work portion will act as a cam to automatically shift the guard out of its path, avoiding any additional bend or any marking of the work.

Another object of this invention is to provide an automatic safety guard for power brakes having the aforesaid attributes, which is reasonably cheap to manufacture, easy to install and efiicient in carrying out the purposes for which it is designed.

Other objects and advantages will become apparent as this disclosure proceeds.

For the practice of this invention, one form for the safety guard, is to have it a horizontally positioned, elongated, light-weight, forwardly facing, obtuse angle channel, close in front of the die parts and swingably depending at its top longitudinal edge from either the ram or the frame of the machine. The lower longitudinal edge of said shield is properly above the top plane of the female die part on the machines bed, to permit admission of the work sheet, but not an operators finger. In a preferred embodiment, the axis of swing of said guard shall be within and close to the vertex of the dihedral angle formed by the first clear vertical plane in front of the machine and the plane reached by the upper surface of the work portion in front of the die at the end of the whipping occurrence. The shield shall be so dimensioned and shaped and its axis of swing shall be so positioned, that the free movement of the sheet part being whipped, is never molested thereby and the sheet in such movement acts cam-wise to shift the shield out of its path. This swingable shield is preferably of transparent plastic and its suspension may be from a vertical panel fixed to either the ram or the frame of the machine. Provision may also be made to adjust the distance of the shield from the front of the machine and its clearance distance from the work being fed into the machine.

In the accompanying drawing forming part of this specification, similar characters of reference indicate corresponding parts in all the views.

FIG. 1 is a fragmentary front view of a power brake equipped with a safety guard embodying the teachings of this invention. Here the safety guard is mounted on the ram of the machine.

3,067,798 Patented Dec. 11, 1962 FIG. 2 is a similar view, but here, the safety guard is mounted on the frame of the machine.

FIG. 3 is a section taken at line 3-3 in FIG. 1. The machine is in normal rest condition and a sheet is placed in position to be worked on. The ram is up.

FIG. 4 is like FIG. 3, but here the machine is shown in condition where the bend in the work has just been completed by bringing the ram down. The safety guard has been automatically shifted to permit the whip unmolested.

FIGS. 3 and 4 are drawn to an enlarged scale.

In the drawing, the numeral 15 designates generally a power brake on whose frame 16, the ram 17 isslidably mounted for movement towards and the away from the machines bed 18. The ram carries the male die part 19, which cooperates with the female die part 20 on the bed, to make a bend 21 across a metal sheet 22, which may be initially laid on a table 23 with its forward edge against a properly positioned stop 24, to determine the position of the line of bend on the work. The mechanism to operate the machine is not shown, because it is well known and forms no part of this invention.

The safety guard indicated generally by the numeral 25 comprises the horizontally positioned, elongated, light-weight, forwardly facing, obtuse angle channel member 26, which is close in front of the die parts 19, 20 and swingably depending at its top longitudinal edge from the bottom edge of a vertical panel 27 which is fixed either to the ram 17 as in FIG. 1, or to the machine frame 16 as is FIG. 2. Attachment of said fixed panel 27 may be by a Z-shaped bracket denoted generally by the numeral 28, which may be of two angle parts 29, 30. Both arms of the part 30 are provided with a slot 31 lengthwise therealong respectively. The numeral 32 indicates a bolt and nut to hold the parts 29, 30 together, and 33 is a bolt to secure part 30 to the ram or frame as the case might be. In FIG. 1, though two are shown, there are a number of brackets 28 spaced along the ram 17, to support the guard 25. In FIG. 2, there is a bracket 28' on each side frame 16; such brackets holding a rigid band 34 which is fixed along the upper edge of the panel 27. The pivotal connection for the swingable guard member 26, may be the piano hinge 35, one leaf of which is fixed to the fixed panel 27, and the other to the guard member 26, as is clearly discernable in FIGS. 3 and 4.

In the set-up as in FIG. 3, when the ram 17 is lowered to make the bend 21 as shown in FIG. 4, the forward part of the work 22 will swing upward, and in its movement must act as a cam to automatically swing the guard 26 upward as shown in FIG. 4. The guard, therefore, must have its rear surface of proper shape and dimension to afford the necessary cam action. In the preferred embodiment illustrated, in order to have the guard 26 near the front of the machine, regardless of its position about its axis of swing, such axis is made quite near the horizontal plane of the top of the female die 20, which plane is that of the top surface of the table 23, and said axis is close to the vertex of the angle A made by the plane P to which the work is finally bent to, and the first free vertical plane P' in front of the machine. Of course, said axis of swing 35 is within said vertex. As seen in FIG. 3, the top edge of the guard 26, abuts the bottom edge of the fixed panel 27, so that the rear surface of the guard nearest the table 23, makes an appreciable angle B, which as shown in this embodiment is about 45 degrees. The bend of the channel member 26, is about equi-distant between the channels longitudinal edges, and the angle of said channel is about degrees. These dimensions and positions are of the specific embodiment shown. 3

It is evident that the parts of the brackets 28, 28 are shiftable by manipulation of the bolts 32, 33, to adjust the position of the safety guard, up and down, and forwardly and towards the front of the machine. When the guard is mounted on the ram 17 as in FIG. 1, the hinge line is brought into the vertex of angle A when the machine assumes the condition shown in FIG. 4. When the guard is mounted on the frame 16 as in FIG. 2, the hinge line is always in its position in the vertex of said angle. Hence the hinge line in FIG. 2 is lower than the hinge line in FIG. 1.

The guard channel 26 should be light enough and its hinge connection 35 free of undue friction, so that even a sheet 22 of light gage can work the guard when such sheet is operated on in the machine. The guard 26 and its suspension plate or panel 27 may be of transparent material as of the plastics known in the trade as Lucite and Plexiglas.

This invention is capable of numerous forms and various applications without departing from the essential features herein disclosed. It is therefore intended and desired that the embodiment herein be deemed merely illustrative and not restrictive and that the patent shall cover all patentable novelty herein set forth; reference being had to the following claims rather than to the specfic description herein to indicate the scope of this invention.

I claim:

1. In combination with a brake having a male die part fixed on a ram which is movable downwardly towards and upwardly from an upright channel-shaped female die part fixed on a fixed bed and having a metal sheet lying across the top of the female die part and extending forwardly in front of the brake, of a safety guard member depending swingably from the brake in front of said die parts and extending sufficiently downward to permit the admission of said sheet between the die parts but to exclude the admission of an operator's finger to the die parts when the sheet is out of the brake; the shape of the rear surface of said guard member being such that when the ram is moved downwardly whereupon the die parts will bend the sheet between them and cause that part of said sheet which is in front of them, to swing upwardly, the movement of said upwardly swinging sheet part will act as a cam to swing the guard upwardly forwardly; said guard member being of such structure that a finger of the operator of the brake is prevented from being passed therethrough to reach between the die parts.

2. The combination as defined in claim 1, wherein the axis of swing of the guard member is on the ram.

3. The combination as defined in claim 1, wherein the axis of swing of the guard member is on the frame of the brake; said brake having a frame.

4. The combination as defined in claim 1, wherein the axis of swing of the guard member is within and relatively close to the vertex of the dihedral angle made by the first freeplane in front of the brake and the plane to which the upper surface of the sheet is swung up to when the ram is lowered.

5. The combination as defined in claim 4, wherein the guard member is a horizontally positioned forwardly opening, obtuse angle channel; the vertex line of said channel being substantially midway between the top and bottom longitudinal edges of said channel; that part of said channel which is above said vertex line when the ram is up, being substantially vertical.

Skoog Aug. 21, 1945 Walldow July 2, 1957 

